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b048a2204d
PE/COFF only has a very limited id space for runtime relocations, and so it defines only a single relocation for movw/movt instruction pairs, which can be combined to load a 32-bit symbol reference into a register. For this to work as expected, these instructions must always appear in the same order and adjacently, and this is something few compilers take into account, unless they target PE/COFF explicitly (and this is not the case for our ELF based toolchains) For Clang 3.6 and later, we can pass the -mno-movt option to suppress movw/movt pairs entirely, which works around the issue. Unfortunately, for Clang 3.5, the option is called differently (-mllvm -arm-use-movt=0) and mutually incompatible between 3.5 and 3.6. Since it is desirable for the CLANG35 toolchain to be usable on newer versions of Clang as well (given that it is the only non-LTO alternative to CLANG38), let's work around this issue in a way that permits versions 3.5 and newer of Clang to be used with the CLANG35 profile. So pass the -mkernel flag instead (and add -Qunused-argument so Clang does not complain about the -mno-unaligned-access in ARM_CC_XIPFLAGS). This also inhibits movw/movt generation, along with some other changes (e.g., long calls) which do affect code generation but not in an undesirable manner. Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org> Reviewed-by: Liming Gao <liming.gao@intel.com>
EDK II Project
A modern, feature-rich, cross-platform firmware development environment for the UEFI and PI specifications from www.uefi.org.
Contributions to the EDK II open source project are covered by the TianoCore Contribution Agreement 1.1
The majority of the content in the EDK II open source project uses a BSD 2-Clause License. The EDK II open source project contains the following components that are covered by additional licenses:
- AppPkg/Applications/Python/Python-2.7.2/Tools/pybench
- AppPkg/Applications/Python/Python-2.7.2
- AppPkg/Applications/Python/Python-2.7.10
- BaseTools/Source/C/BrotliCompress
- MdeModulePkg/Library/BrotliCustomDecompressLib
- OvmfPkg
- CryptoPkg/Library/OpensslLib/openssl
The EDK II Project is composed of packages. The maintainers for each package are listed in Maintainers.txt.